Keratoconus
At a glance
Progressive corneal ectasia causes thinning and irregular astigmatism. Document progression with reproducible measurements.
CAVE
- Sudden pain or opacity may indicate acute hydrops.
- Young age and eye rubbing increase concern about progression.
Clinical presentation
- Changing astigmatism, reduced spectacle-corrected acuity, ghosting and asymmetric corneal shape.
Diagnosis & investigations
- Obtain refraction, best-corrected acuity, slit-lamp examination and corneal tomography with anterior/posterior elevation and pachymetric distribution. Compare the thinnest point, curvature and posterior surface on the same instrument with reliable acquisition.
- Repeat inconsistent scans and consider contact-lens warpage before diagnosing progression. Use concordant changes beyond measurement noise across more than one parameter; a single Kmax change is not sufficient in every eye. Record eye rubbing, atopy, family history, age and vision with the current correction.
Differential diagnosis
- Pellucid marginal degeneration, contact-lens warpage, postsurgical ectasia and other corneal irregularity.
Treatment
- Stop eye rubbing and treat allergy; separate the aim of halting progression from optical rehabilitation. Cross-linking does not eliminate the need for lenses, and improved lens vision does not remove a cross-linking indication.
- Select epithelial-off or other protocols using the evidence and safety requirements of the specific technique, particularly minimum intraoperative stromal thickness. Intracorneal ring segments may improve corneal shape in selected eyes but are not a universal substitute for stabilisation.
| Finding | Action | Timing / detail |
|---|---|---|
| Stable ectasia with useful spectacle vision | Spectacle correction, allergy control and avoidance of eye rubbing | Repeat measurements to establish stability, especially in younger patients |
| Irregular astigmatism limiting spectacles | Rigid corneal or scleral contact lens fitting; evaluate comfort, corneal health and handling | Better lens acuity does not show that ectasia has stopped progressing |
| Documented progression or high-risk young patient | Prompt corneal assessment for cross-linking; verify protocol-specific thickness and suitability | The primary goal is stabilisation, not guaranteed spectacle independence |
| Acute hydrops or scar with poor corrected vision | Urgent corneal review for hydrops; protect the surface and manage pain/IOP, considering procedural options in selected cases | For advanced scar/intolerance, discuss DALK or penetrating graft according to depth and endothelial status |
Follow-up
- Young patients, recent refractive change or suspected progression commonly need repeat tomography within 3–6 months; stable adults can often be reviewed at 6–12 months. Use shorter intervals when rapid progression is plausible. After cross-linking follow the procedure-specific healing and infection surveillance plan, then resume comparable serial tomography.
Risk factors & context
- Ask about eye rubbing, atopy and family history.
- A good corrected acuity does not establish that the ectasia is stable.
Complications
- Progressive irregular astigmatism, contact-lens intolerance, scarring and acute hydrops can compromise visual rehabilitation.
When to refer
- Refer for suspected progression, inadequate optical rehabilitation or acute hydrops.
References 2
- AAO · Corneal Ectasia Preferred Practice Pattern ↗2024 · Diagnosis; progression; cross-linking; visual rehabilitation
- Belin et al. · Determining Progression in Ectatic Corneal Disease ↗2020 · Measurement noise; multidimensional progression assessment
Adapt to the patient, local pathways and authorised product information.